Family data were collected on 174 relatives of 10 severely obsessive-compulsive patients. No instances of obsessive-compulsive disorder were located, although 11.6% of first degree relatives had been hospitalized for other psychiatric illness. These rather isolated families had cultures which emphasized cleanliness and perfection, but other family members did not develop rituals or obsessive rationales as the patient did. Typically one or both parents involved in an unfulfilled marriage directed symbiotic needs toward the patient. Parents and offspring became trapped in an increasingly powerless struggle against symptoms which acted as a barrier to closeness, but which also prevent the patient from developing an autonomous existence. Parental symbiotic needs combined with perfectionist family styles, possibly superimposed on a constitutional vulnerability to psychiatric disturbance, appear to form a major contribution to obsessive-compulsive disorder.